"It got to the point where my kids were getting older, and it was way past the point that they noticed it. And I noticed that they noticed. That's enough to straighten you out," shares the dad of Gracie, 17, Maggie, 15, and Audrey, 12.

"I drank too much. I partied too much. And did other things too much. Chemically," says McGraw. "No needles or that kind of stuff, but … use your imagination."

In fact, McGraw saw himself heading in the same direction as late country singer Keith Whitley, who died of alcohol poisoning in 1989.

"Keith Whitley taught me how demons can overtake you if you let 'em. And I was headed down that path. You feel like you're supposed to be 'on' all the time. Then you drink and get onstage, and all of a sudden you feel confident and powerful."

"It becomes a habit. Up until seven years ago, there were not a lot of shows that I didn't have something in my system," the singer adds.

Now with his demons behind him McGraw – who will be on tour this summer ahead of his new album Sundown Heaven Town (due Sept. 16) – can laugh about his past, and especially about all the pounds those bad habits put on him.

"I was looking at some old concert shots the other day. Man, my gut!" he says. "I was up there in a see-through shirt – I thought I was lookin' good!"

For more on McGraw, download the new issue of Men's Health magazine, available digitally today.